Pipe conveyors, also referred to as tube conveyors, are conveyor belts which are loaded with a material to be conveyed and after being loaded are closed into the conformation of a tube by mechanical means to force the conveyor into a closed tube by overlapping the belt edges. After being closed into the form of a tube the material being conveyed is protected from external elements and is also contained within the tube to in help prevent loss of the material being conveyed. In any case, a plurality of support and guide assemblies for the conveyor are situated along the conveyor path to open and close the conveyor as desired at different points along the path of the conveyor. Each assembly includes a plurality of support and guide rollers, which contact and hold the pipe conveyor belt while in operation.
Pipe belts are predominantly employed where bulk material is conveyed in a relatively confined space through horizontal and vertical curves. By virtue of their special adaptability to various topographical conditions, pipe belt conveyor systems are also used for conveying material over distances longer than 1 kilometer. The advantages offered by pipe belts include protection of the transported material against environmental influences (rain, wind, etc.) and protection of the environment against material dropping from the conveyor belt (ashes from power plants; gypsum etc.). In some cases pipe belts also protect the material being transported for theft by employees and third parties that may be present in the area through which the material is being conveyed.
Pipe conveyor belts are prone to running off course or twisting under certain operating conditions. Belts may twist because of uneven loading, uneven guidance through curves, or otherwise poorly aligned systems. Support and guide rollers are optimally designed to provide for trouble-free and low maintenance operation as the pipe belt travels through the conveyor system. Said rollers are individually aligned depending upon the course that the conveyor system is running. The functionality of said rollers is influenced by varying weather and temperature conditions, wear, and design defects. For example, moisture reduces friction between the rollers and the conveyor belt, which results in guidance that is not optimal. If the pipe conveyor belt is misaligned or twisted, for example as it is running up on an ejecting drum, the conveyor belt can fold or even run off of the drum sideways.
Many pipe belts include metal reinforcements to make the pipe belt stronger and to increase its durability. These reinforcements can cause the overlap section of the belt to be heavier than the rest of the belt, since there are two reinforced areas sitting on top of one another. This top heavy design can cause the belt to rotate as the belt encounters horizontal or vertical curves. Such a rotation of the pipe belt can lead to substantial belt damage and loss of the material being conveyed. Accordingly, undesired rotation of the pipe conveyor belt should be avoided and the problem should be corrected as soon as possible to limit prevent or minimize damage to the system and loss of material.
Some of the technology disclosed in the prior art forcibly guides the conveyor belt over finger rollers projecting into the cross section of the pipe belt. This guidance method is afflicted with the substantial drawback that the conveyor belt can be damaged by the finger rollers. Consequently, this method does not represent a totally satisfactory or permanent solution to the aforementioned problems associated with undesired rotation of pipe conveyor belts within conveyor systems.
For these reasons, there is a need for a system to monitor the orientation of pipe belts as they travel through conveyor systems for undesired rotation to correct problems associated with unwanted rotation of the belt before substantial damage or loss of material occurs. It is also desirable to monitor such pipe belts for other types of belts damage, such as rips and tears, to minimize damage.
U.S. Pat. No. 6,702,103 discloses a device for monitoring a tubular belt conveyor system, comprising the following: a conveyor belt consisting of an elastomeric material, especially with embedded tie rods, the conveyor belt being closed to form a tubular belt by overlapping its longitudinal edges so as to form an overlap area; other system parts, i.e., a driving drum, a tail pulley, support rollers, guide rollers, supporting structures and optionally, other parts. The inventive device is characterized in that the device for monitoring the overlap area of the tubular belt is provided with an optoelectronic system. In the event of a deviation from the desired conveyor belt overlap, the optoelectronic system initiates a correction of position by means of the guiding rollers. If the corrective measures are not taken within a certain period, the tubular belt conveyor system is automatically disconnected.
U.S. Pat. No. 6,712,199 describes a device for controlling and monitoring a conveyor belt which is made of rubber or a rubber-like plastic material and preferably provided with embedded reinforcements. By overlapping of the longitudinal edges of the conveyor belt the belt can be closed such that it forms a tubular conveyor belt which is supported on all sides by idler wheels. The device also comprises at least the following components: at least one detectable element which is integrated into the conveyor belt and notably takes the form of several elements which in the longitudinal and/or transverse direction are positioned at distances from each other; and at least one scanning unit with which the precise position of the belt can be determined in a non-contacting manner by detection of the element or elements. The device provided for by the invention is characterized in that the detectable element is an induction loop and/or a transponder, a metal particle or a permanent magnet. The scanning unit is advantageously configured as a system of several detector elements which form a detector chain.
U.S. Pat. No. 8,157,085 discloses a device for monitoring a conveyor belt in which a sensor can be fixed easily to the body without using any special fixing device and the properties of the conveyor belt can be detected with high precision. The device for monitoring the conveyor belt comprises a body to be detected embedded in a conveyor belt running endlessly, and a sensor provided oppositely thereto in the body. The sensor detects the variation in properties of the conveyor belt by detecting variation of the body to be detected due to the variation in properties of the conveyor belt. The sensor is secured to a shaft which supports a hollow roller for guiding the conveyor belt in the conveyance direction rotatably on the body in the roller thus making the sensor itself nonrotatable.
U.S. Pat. No. 5,161,675 teaches a tubular belt conveyor system includes a conveyor belt having a cross-sectionally closed, curvilinear, tubular configuration including a zone of overlapping edge portions. A plurality of support and guide assemblies for the conveyor are situated along the conveyor path. Each assembly includes a plurality of support and guide rollers held about the cross-sectionally closed conveyor belt in a contacting relationship therewith. In each assembly one roller is in engagement with the cross-sectionally closed conveyor belt at the edge overlap. The closed tubular configuration in each length portion of the conveying path has an oval cross section. The support and guide rollers force the conveyor belt into the closed tubular configuration of oval cross section. The first support and guide roller of each assembly is settable onto the zone of overlapping edge portions.